There are multiple errors in _dl_tlsdesc_dynamic:
- the reference C implementation should return pointer to the
thread-local variable, not offset from the thread pointer, because the
xtensa ABI expects TLSDESC_FN to return pointer to the TLS variable;
- addx8 used for indexing into dtv has its second and third registers in
wrong order, the index must be multiplied by 8, not the base;
- the same addx8 uses wrong base: instead of dtv it adds the offset to
the threadptr;
- the return value in the fast path is calculated as
td->tlsinfo.ti_offset - __builtin_thread_pointer, not what was
intended;
- both fast and slow paths should not subtract __builtin_thread_pointer
from the result.
Signed-off-by: Max Filippov <jcmvb...@gmail.com>
---
ldso/ldso/xtensa/dl-tlsdesc.S | 21 +++++++++------------
1 file changed, 9 insertions(+), 12 deletions(-)
diff --git a/ldso/ldso/xtensa/dl-tlsdesc.S b/ldso/ldso/xtensa/dl-tlsdesc.S
index 6f417f61a98b..426f2180b3c0 100644
--- a/ldso/ldso/xtensa/dl-tlsdesc.S
+++ b/ldso/ldso/xtensa/dl-tlsdesc.S
@@ -39,7 +39,7 @@ END (_dl_tlsdesc_return)
The assembly code that follows is a rendition of the following
C code, hand-optimized a little bit.
- ptrdiff_t
+ void *
_dl_tlsdesc_dynamic(struct tlsdesc_dynamic_arg *td)
{
dtv_t *dtv = (dtv_t *)THREAD_DTV();
@@ -47,8 +47,8 @@ END (_dl_tlsdesc_return)
&& dtv[td->tlsinfo.ti_module].pointer.val
!= TLS_DTV_UNALLOCATED)
return dtv[td->tlsinfo.ti_module].pointer.val
- + td->tlsinfo.ti_offset - __builtin_thread_pointer();
- return __tls_get_addr (&td->tlsinfo) - __builtin_thread_pointer();
+ + td->tlsinfo.ti_offset;
+ return __tls_get_addr (&td->tlsinfo);
}
*/
@@ -65,33 +65,30 @@ HIDDEN_ENTRY (_dl_tlsdesc_dynamic)
/* && dtv[td->tlsinfo.ti_module].pointer.val != TLS_DTV_UNALLOCATED) */
l32i a6, a2, TLSDESC_MODID
- addx8 a6, a3, a6
+ addx8 a6, a6, a4
l32i a6, a6, 0
beqi a6, -1, .Lslow
/* return dtv[td->tlsinfo.ti_module].pointer.val
- + td->tlsinfo.ti_offset - __builtin_thread_pointer(); */
- l32i a6, a2, TLSDESC_MODOFF
- sub a2, a6, a3
+ + td->tlsinfo.ti_offset; */
+ l32i a5, a2, TLSDESC_MODOFF
+ add a2, a6, a5
abi_ret
- /* return __tls_get_addr (&td->tlsinfo) - __builtin_thread_pointer(); */
+ /* return __tls_get_addr (&td->tlsinfo); */
.Lslow:
#if defined(__XTENSA_WINDOWED_ABI__)
mov a6, a2
movi a4, __tls_get_addr
callx4 a4
- sub a2, a6, a3
+ mov a2, a6
retw
#elif defined(__XTENSA_CALL0_ABI__)
addi a1, a1, -16
s32i a0, a1, 0
- s32i a3, a1, 4
movi a0, __tls_get_addr
callx0 a0
- l32i a3, a1, 4
l32i a0, a1, 0
- sub a2, a2, a3
addi a1, a1, 16
ret
#else
--
2.1.4
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